With development of an IP multimedia subsystem (IP Multimedia Subsystem, IMS for short) and introduction of evolution packet core (Evolution Packet Core, EPC for short), a legacy core network based on circuit switching is evolving into a network based on IP packet switching at an ever-increasing pace, and increased use of IP-based signalling is found at a bottom layer. This results in the Diameter (Diameter) Protocol being widely applied to architectures such as IMS, policy and charging control (Policy and Charging Control, PCC for short), and EPC. Diameter signalling is used for interaction between many network elements, such as a home subscriber server (Home Subscriber Server, HSS for short), a mobility management entity (Mobile Management Entity, MME for short), a policy and charging rule function (Policy and Charging Rule Function, PCRF for short), and an online charging system (Online Charging System, OCS for short). To support inter-operator roaming and interworking, many operators start to consider deploying diameter edge agents (Diameter Edge Agents, DEAs for short) on network boundaries and building Diameter signalling networks.
The operators' efforts to set up DEA nodes and build Diameter signalling networks are mainly driven by the need to hide a network topology. As defined in related standards, fundamental network topology hiding principles are: hiding names of all Diameter nodes, and hiding the number of Diameter nodes on a network. In a scenario of inter-operator international roaming by EPC subscribers, Diameter nodes specifically refer to MMEs, and DEA deployment helps to hide architectures of the operators' internal networks, thereby protecting security of the operators' networks, specifically, preventing a visited network operator from learning about an architecture of a home operator's network. EPC roaming mainly involves S6 interfaces between MMEs and HSSs. An existing solution of hiding an operator's network topology in EPC subscriber roaming scenarios is to replace a real name of a home MME of the subscriber with a fixed virtual name and to use the virtual name for subsequent roaming related processing. However, this one-to-one fixed replacement is unable to hide the number of Diameter nodes on a network, and does not satisfy the fundamental principle of network topology hiding. Another implemented solution is to perform many-to-one replacement whereby a same DEA may process information sent by a plurality of MMEs on an operator's network, and the DEA may replace names of all the MMEs on the operator's network with a unique virtual name. This many-to-one replacement may hide the number of Diameter nodes, but it renders a home MME of a subscriber unable to be determined, which in turn leads to failures in completing a location delete procedure, which is triggered when an EPC subscriber leaves a roaming destination, or failures in subscriber data management operations (for example, inserting subscriber data or deleting subscriber data) initiated by an HSS.
The foregoing network topology hiding solutions, including both the one-to-one fixed replacement and the many-to-one replacement, suffer from different aforementioned drawbacks, and consequently compromise the effectiveness of network topology hiding.